Agreed. There are millions of Catholic with little to no understanding of the things of their faith. This is to our shame and is a reason why your wife is blessed to have met you - she may never have "met" Christ in a real way within the Church but now is now bound for Heaven (unless I miss my guess). Despite all of my serious disagreements with much of Protestantism. I am infinitely more pleased with a "cradle Catholic" getting saved there than staying here in ignorance (not the same thing as calling her ignorant).
That having been said. If you had decided (perhaps with a group of other Christians), to observe two days of prayer and fasting (Scriptural, you agree?) - say over the financing of a new church building project or a missions project - and you then decided you were too hungry to continue so you snuck a cheeseburger. Would you not feel you had sinned?
God bless you IMRight...and I would say the same right back at you!
grace and peace to you.